Ophthalmic surgery sometimes involves the formation of an ocular incision, for example, in the cornea or sclera. For example, in cataract surgery, an incision is made in the sclera which enables the surgeon to remove the natural lens of the human eye and replace it with an implant known as an intraocular lens. Recent developments in intraocular lens technology have resulted in making the optic of the intraocular lens of soft, flexible material. This enables the intraocular lens to be rolled, folded or otherwise deformed for insertion through the natural lens extraction incision. Consequently, the incision can be of shorter length than is possible for a rigid or non-foldable intraocular lens.
A small ocular incision is very desirable for a number of reasons. For example, a small ocular incision minimizes trauma to the patient, heals more rapidly than a larger incision, and is less subject to infection.
An ocular incision is typically closed with a suture which is commonly considered as comprising a suture needle and a filament attached to the needle. The suture can be used in several different ways to close an ocular incision made in cataract surgery. For example, interrupted stitches can be used, and with this technique, an array of separate stitches are extended transversely across the ocular incision. Alternatively, running stitches which run continuously in zig-zag fashion across the incision may be employed. Finally, a combination of interrupted and running stitches may be utilized to close the ocular incision.
For small ocular incisions of the type used for flexible IOL's, the stitches may take the form of an "X", infinity symbol, or multiple loops through the incision. It has also been proposed to utilize a single stitch running longitudinally of the incision.
One reason that the suturing technique is very important for an incision in the cornea or sclera is that, for some types of stitches, the filament can induce astigmatism. This is the result of the forces exerted by the filament on the cornea or sclera. Prior techniques known to applicants create some likelihood of surgically induced astigmatism.